Electric wattmeter.



P. M. LINCOLN.

' ELECTRIC WATTMETER. APPLICATION FILED Nov. 5. 1 913.

1,156A12. Patented 0m. 12, 1915.

5 SHEETSSHEET L FIEJI- INVENTOR LINCOLN. ELECTRIC WATTMETER. APPLICATION FILED NOV. 5. 1913.

Patented Oct. 12, 1915.

5 SHEETS-SHEET 2 6 A a. E

F! GE.

HEY-

P. M. LINCOLN.

ELECTRIC WATTMETER.

APPLICATION FILED NOV. 5. I913. 1,156 412, Patented 0013.12, 1915. v

5 SHEETS-SHEET 3.

F' HEW- WITNESSES R 39 INVENTO P. M. LINCOLN;

ELECTRIC WATTMETER. APPLICATION FILED NOV. 5, 1913.

1,156,419. Patented Oct. 12, 1915.

5 SHEETS-SHEET 4.

WITNESSES INVENTOR P. M. LINCOLN.

ELECTRIC WATTMETER.

APPLICATION men Nov. 5, I913.

- 1,156,412, Patented Oct. 12, 1915.

5 SHEETS-SHEET 5.

FIRM- 42 m a I vl'lvlwlvlvlvlvfl l 4 WITNESSES INVENTOR M @MM rain. M. LrNcoLN, of PITTSBURGH, PENNSYLVANIA.

ELECTRIC WATTME'IER.

Specification of Letters Patent.

Patented Oct. 12, 1915.

Application filed November 5, 1913. Serial No. 799,320.

To all whom it may concern:

Be it known that I, PAUL M.'LINooLN, a citizen of the United States, residing at Pittsburgh, in the State of Pennsylvania, have invented certain new and useful Improvements in Electric Wattmeters, of which the following is a specification.

My invention relates generally to means for measuring electric power. It is more particularly concerned with such instruments as measure the differential effects of two circuits derived from the circuit to be measured and energized respectively in proportion to the voltage and in proportion to the current of the circuit to be measured.

The primary object is to produce a more direct, simple, accurate and reliable device for measuring electric power.

Other objects are to produce an instrument that will accurately indicate energy and at the same time permit of an adjustable and sufiiciently large lapse of time between the occurrence of an energy flow and its indication; to produce a superior maximum demand and integrating wattmeter, and to generally improve such instruments as will hereinafter appear.

I have illustrated the invention in several preferred forms in the accompanying drawing, wherein Figures I and II are diagrams of simple circuits to illustrate the principle of my invention. Fig. III is a diagram illustrating one method of using the differential effects of two currents. Figs. IV and IV show respectively in horizontal section, and a partial vertical section along the line (IV*) of Fig. IV, one form of construction for thermo battery. Fig. V is a diagram illustrating the use of athermo battery to measure the wattage of an alternating current- 'circuit.- Figs. VI, VII, VIII, and IX, are diagrams illustrating several forms of connection for taking ofl the required currents from an alternating current circuit. Fig. .X represents still another form of structure for indicating the eifects of the two superposed currents, and alsgsa device for integrating the total amount of energy used in the circuit. Fig. XI shows a modified form of arranging the heating elements or eXpansible tubes in Fig. X, as will hereinafter be described. Fig. XII,is a diagram and partial vertical section of another form of mechanical construction for indicating the electric power.

Generally stated I measure electric energy by measuring the difierence in the thermal or electrical effects obtained by superposing on each other two derived currents which are proportional respectively to the voltage and to the amperage of the circuit to be measured. For example, in Fig. I, supposing the generator G to be sup plying the line containing the load L; if we take two taps i i", at the end of a series shunt S, the current ,flowing through these taps will depend upon the resistance R of the shunt circuit, and will always be proportional to the current into the load L. Likewise, if we connect the resistance R to the opposite side of the circuit by a shunt lead 6 containing resistance r, the current voltage, (E,) alone, the heating as well as other effects due to the current will be the same in the two parts of the resistance R; but when these are superposed the circuit will have the sum of the effects of current I and voltage current E, whereas the lead a" will have the dilference between the eifects of current I and current E. 'It is evident that an instrument designed to 0perate by the differential effects of the currents E and I during any period of time will give an indication proportional tothe product of the current and voltage on the load, and therefore indicate the energy orwatts in the main circuit.

As a further illustration of the principle, consider Fig. II: Assuming that in the net work of wlres indicated 'we have four equal.

resistances A, B, C, D; evidently a current flowing from-E 'to E will divide equally through the four resistances as indicated. Likewise the current flowing from I to 1,, will divide equally, one half traversingeach of the four leads as indicated by the small arrows. The heating or any other electrical effects in the conductors A and C will therefore plainly be proportionalto the difference between-the values of the current I and the current E; whereas the effects 1n the conductors B and D will be proportional to thesum of the currents I and E.

In some instances, I apply this principle by D, as the using the conductors A, B, C, heating elements of a thermo-electric battery, in.which the diiierence in temperature which the currents E and I are taken, as

I hand, and B, D, on ,the other hand. Or

'tionall above described. This'may be shown to be true for either direct or alternating current and in the latter case takes cognizance of the phase angle between them, thereby giving true energy in any case. instanees,"I-' use electric energy directly, as by operatingidynamometers by the respective currents in the limbs A, C, on the one again I make use of the heat produced by the combined derived currents to operate other indicators directly.

In Fig. III, I have arranged resistance elements A, Bi, C, D, corresponding to the elements A, 'B, G, D, in Fig. II. If we pass the current due to the voltage of a circuit to be measured, through the net workas indicated by the arrows," it is plain that the elements A and C will be heated proporto the difference between the currents and I, and elements B and D will be heated proportionally to the sum of the currents. E and I. Therefore the difference between the temperature of the pair of elements A, C, on the one hand, and the temperature of the pair of elements B, D, on the other'hand, will .measure the total energy or watts of the circuit. I therefore measure this diiference of temperature in any convenient manner, as for example, by' measuring the voltage developed by a thermo-electric battery with opposite joints heated respectively by these pairs of'resistance elements. A. convenient mechanical embodiment of such a device is shown in Figs. IV and IV; Here the bars A B .6 D are the conductors'A, B, O, D, of

' battery 18 and 19 are connected with avoltmeter V. These bars 16 and 17 are preferably made of-diflerent cross-sections, in inverse proportion to their thermal conductivity, so;.tliat the aggregate heat conduction o'f'all the bars '16 is equal to that of all-the bars 17{ thermal and electric conduc- In other tivity are always in constant ratio, the electric conductivity .is thus made equal. The heating bars, as shown in Fig. IV, especially are covered withinsulation 20 and also surrounded by a heat reservoirZl, pref erably consisting of heavym tal concentric rings; While the entire system of bars is' covered by a heat-and-electric insulator 22. Contiguous to the bars 16,17, I place heat conductors 23, with radiating wings 23. By thismeans I prevent the escape of any heat otherwise than by traversing the bars 16, 17, and 23, 23, and subsequent radiation by the cooling wings 23 attached to thebars 23, 23. By use of the adjustable heat reservoir 21, I provide for anadjustable, time lag between the flow of energy and its indication by the meter; so that the indicating I call a logarithmic average indication,

because the indication of the energy approaches its true value along a logarithmic curve and according to a law by means of which the actual' energy maybe shown when the time lag is determined. I shall hereafter describe another indicator for maxi mum demand.

It will be understood that in dealing with alternating current, the phase relation between current and voltage is important; but it should be noted that a net work such as indicated in Fig. I or such as physically embodied inthe device of Fig. IV, will still 'operate to indicate the true energy,'no matter what the phase relation between the current instrument V may indicate at any time, not

directly additive to or'subtractive from, the -'quantity E in the diagram, yet the difference in heat losses inthe cool and hot limbs of the thermo-battery is proportional to that function of E and I whichls the expression for the true energy of an alternating current; so that still a measure of the difierence of temperature of the two sides of the heated net work is a true measure of'energy and is independent of phase relation. Thus in the diagram of Fig. V, "if we have an alternating current source 24 in circuit with the load L,

wemay, by the primary 25 of a series-transformer, whose secondary is 26, take] off the current I proportional to the amperage; and by another primary 27, of a shunt transformer whose secondary is 28, we may take 01f aburrent E proportional .to the voltage. These respective currents may be employed -for example, to operate a thermo battery 16, "17, by .means of resistance as before described for Fig. IV, and will give an indication of the true energy.

In various. ways the apparatus for dealing with alternating currents may be simplified and varied to suit conditions. For example, in Fig. VI, we may use a two part net work 2930 instead of a four part net work by taking a middle tap on the secondary 26 of the series transformer for the current element and connecting it in series with the secondary 28 of the shunt transformer for the voltage element, the other end of secondary 28 being connected to the middle point of the two part resistance 29, 30. Again as shown in Fig. VII, the terminals of the current transformer secondary 26 maybe connected at one end to the middle point of a two-part resistance 31, 32, and the other end connected to the middle point of the secondary 28 of the voltage transformer.

As shown in Fig. VIII, the voltage transformer may be entirely dispensed with by connecting the middle point of the secondary 33V to the primary 34, while its terminals connect to resistance 35, 36, the middle point of-which is in turn connected to the opposite potential through a resistance 37. Again, the current transformer may be dispensed with as shown in Fig. IX, by connecting the line leads respectively to the middle point of the secondary 38 of the voltage transformer and the middle point of the two part resistance 39, 40, in turn connected to the terminals of the secondary 38.

It will be understood that for a given total loss in heating elements, the difference of temperature between the pair of elements A, C, and the pair B, D, will be a maximum, and therefore give the maximum accuracy in the wattmeter when the losses in the heating elements due to the voltage current alone is approximately equal to the losses due to the current element alone; that is, E should be equal to I for full load conditions. Also, accuracy will be increased by making the apparatus independent of temperature conditions of the surrounding atmosphere. For this reason, I prefer to make the Voltmeter V of a material having the same temperature co-efiicient as the heating members A B C D in Fig. IV. Thus as the resistance of the voltmeter increases demanding a higher voltage to cause a given inclication, the heat loss in the heating element also increases, giving a proportionally higher temperature difference between the two ends of the thermo battery.

Instead of using the heat developed by the currents proportional respectively to the current and to the voltage of the line to be measured to operate a thermo battery, I may use it to produce direct mechanical motion,

. as illustrated 'in Figs. X, XI,- XII.

In Fig-X, the generator 41, leads 42, and

vided with a pointer 61 traveling over a.

scale 62. These tubes 55, 56, are preferably formed with deeplycorrugated sides, closed entirely and filled with some liquid easily expansible by heat, such as kerosene. The tubes are free to expand longitudinally when the fluid expands by reason of the heat of the loops 53, 54. Obviously when the two tubes expand the sameamount there is no indication of the pointer 61; but if one tube expands more than the other the pointer 61 will travel sidewise, the tubes moving on their pivots 5'7, 58. From the previous discussion it will be obvious that the current I alone flowing from the lead 42, through the loops and 54, in parallel and back to the ends of the secondary 45, will cause the same expansion in each of the tubes 55 and 56, by equally heating the fluid therein. The current E induced from the shunted primary 44 into the secondary 45, will traverse the path indicated by the arrows marked E, and obviously when superposed on current I will act differentially, causing a heat due to the sum of E and Tim one leg and due to the difference in the other. The result will be the greater expansion of the tube 56 than the tube 55 and the pointer 61 will move to the right, thus indicating the wattage of the main circuit. I may obviously use the metal of the tubes 55, 56, itself as the heated conductors 53, 54. Such an indicating device as above described may also be conveniently supplied with an integrating device. As anillustration, I have shown in this Fig. X an integrating mechanism controlled in its movements by the pointer 61. The constant speed motor or clockwork m, by shaft n, worm 0, and gears 7), drives a friction table 9 which engages a friction wheel 1' fixed to a shaft 8, which shaft is free to move longitudinally so that its speed depends upon the position of the friction wheel 8 with respect to the center of the table 1 This position of the friction wheel is determined by the wattmeter pointer 61 which is attached to shaft 8 by a cord 25 with a universal bearing M. It will be understood that the shaft 8, by a pinion 41 splined thereon, drives any suitable gearing w, carrying any desired indicators after the usual manner of integrating wattmeters. It will be clear that the departure of friction wheel .5: from the centerof the table g is always proportional'to the scale indication of the pointer 61. This can be. provided for,

if necessary, by the shape of thebase w su porting the flexible link or cord t, -as will e understood. The link 25 is kept taut by re- .tractile spring y at the endof shaft 8'. As

the pointer '61 is moved fromzero position, it may of course push along an idle pointer 62*, in the usual manner, to indicate the maximum or-extreme position of the pointer 61, thereby showing the maximum logarithmic average demand. As shown in Fig. XI expansible tubes 55, 56, may be made as part .of large reservoirs $5 56, in the form of tubes having'an ad. ustable series of blocks55", 56", arranged.-

to absorb heat by conduction from the walls andbottom of the reservoirs, so astovary the amount of heat storage. In this case also I preferably arrange the heating wires corresponding to the loop conductors 53, 54;, of Fig. X, bywinding' them about the reservoirs 55 56*. By this means I use a volume of fluid which islarge in comparison with the volume of the expansible tubes and thus not only exaggerate the indication but provide for any desired amount of time lag in the action as by varying the amount of liquid or the number of the blocks 55 and 56".

As above stated the currents respectively proportional to amperage and voltage ought to be equal in volume at full deflection, in

: order to get maximum accuracy; and while this condition is easily arranged by means of the. transformers, when dealing with alternating currents, it imposes a difliculty 40 1 will waste energy when the useful voltage drop between the point a and the lead 2" f has the same value in operating with the whenfiggorking' with direct current, because there Would be an undue waste of energy. 'Iihus the resistance in element 1 of Fig. 1,

driving the table gtherein, I use a constant ,j speed electric motor-c," and connect its shaft d with a small-armature 'e'running the fields f, f, excited directlybyseries windinghaving. the main current from the line circuit' 42, 43, to be measured. By proper winding of fields f, f, and armature "e we may obtain any voltage desired atth'ecoinmutator 9, but it will always -beproportional to the j current of .the circuit whose .I mwer'is to measured;- As before,=tlie current E and zthis'current Itraverse one limb of the net wiork in expansion tubes -55,' '56,in, the sam frors and uncertainties of similar. instru ments heretofore used; with, other' advan tages; which will be obvious tothose faIi 1'iliar,.-;v

direction, and the other limb in opposition, v as will be obvious from the arrows in the figure. I V

The fields-,-,-f, maybe in some cases, especiallywheifdealing with large currents,

excited'bya smaller current by using a series shunt as h, connecting it in by closing the switch 71. It will be obvious also, that instead of changing the ratio' of amperage element by the use of fields f, f, we' n1ay change the ratio-of the voltage element by exciting these 'fields with windings taken across the voltage of the machine, thus getting from the commutator g a current of larger volume and .lower voltage. In such case this current would properly be combined with a current from the series shunt.

It, for measurement. In either case it will be seen that we properly adjustth'e ratio of V currents employed in measuring, to the full sistance losses. I

In all the devices described, I employ the same principle of ,indicatingthe energy of the electric circuit .by the diiferential efl'ects obtained by superposing a current proportional to-the amperage of the circuit, and a current proportional to the voltage of the circuit, combining said two effects to operatev an'indicator. It will be understood that my. invention. is not limitedto one pair of heating elements or other devices for making thei ndicat ons, and that the invention is applicable topolyphasecircuits by using a plurality (if-pairsof heating elements, as

line current, withoutin'curring serious reby merely duplicating the actuating'devices f}.

of Fig. XI, for, example, also duplicatingthe transformers. I provide 'for uniformity and 1 certainty'of action, especially -ir'i thefheatf operating devices, and eliminate many er With the art;

It is evident that I may use as; an indi cato-r any device that is responsiveto'the.

passage of current, so long as it hasthe two requisltes, (a) that it takes no cognizance of the direction of current flow; and. (b)

that it has a response proportional to the square of the current flowing.

Having thus described my invention, and

illustratedits use, what I claim is; '1 1. wattmeter comprising two derived circuits each traversed by two superposed currents 'one'of which is proportional; to the voltage. and the other-to the. amperage-of the circuit the energy of which'yiis. to be meats-:-

rure'd, the said currents being additive in one of the circuits and'opposed in the other,-

means associated witheachof the sai d derived circuits. for receiving and-temporarily),

storing, during a definite time period, the

energy efl'ects therein, and .means indicatg the difference-between. the average stored energy effects of the derived circuits, during said predetermined time period, substantially as described.

2. A wattmeter comprising two derived circuits each traversed by two superposed currents one of which is proportional to the voltage and the other to the amperage of the circuit the energy of which is to be measured, the said currents being additive in one of the circuits and opposed in the other, devices associated with each of the said derived circuits'for receiving and temporarily storing the heat produced therein, means for adjusting the ratios of the thermal capacities of the heat-storage devices to the rate at which heat is radiated therefrom, and means for measuring thedifference of the average heating elfects of the derived circuits during a predetermined time period.

3. A wattmeter comprising two derived circuits each traversed by two superposed currents one of which is proportional to the voltage and the other to the amperage of the circuit the energy of which is to be measured, the said currents being additive in one 01' the circuits and opposed in the other, devices associated with each of the said derived circuits for receiving and temporarily storing the heat produced therein, means for measuring the difference of the average heating effects of the derived circuits during a predetermined time period, and integrating mechanism controlled by the said indicating means.

l. A, wattmeter comprising two derived circuits each traversed by two superposed currents one of which is proportional to the voltage and the other to the amperage of the circuit the energy of which is to be measured, the said currents being additive in one of the circuits and opposed in the other, devices associated with each of the said derived circuits for receiving and temporarily storing, during a definite time period the heat produced therein, means for indicating the difference of the average heating effects of the derived circuits during a predetermined time period, and a maximum demand index actuated by the said indicating means.

5. A wattmeter comprising two derived circuits each traversed by two superposed currents one of which is proportional to the voltage and the other to the amperage of the circuit the energy of which is to be measured, the said currents being additive in one of the circuits and opposed in the other, two expansible bodies having adjustable time lag respectively heated by the currents traversing the said circuits, and an indicator actuated by the relative expansion of the said. bodies.

6. A wattmeter comprising two derived circuits each traversed by two superposed currents one of which is proportional to the voltage and the other to the amperage of the 'thesaid currents being additive in one of the circuits and opposed in the other, a plurality of actuating elements having adjustable energy-storing capacity diflerentially afiected by the superposed currents in the said derived circuits, and means to indicate the average difierential effects of the said superposed currents on the said actuating elements. I

7 A wattmeter comprising two derived circuits each traversed by'two superposed currents one of which is proportional to the voltage and the other to the amperage of the circuit the energy of which is to be measured, the said currents beingadditive in one of the circuits and opposed in the other, a plurality of actuating elements having definite and adjustable energy-storing capacity differentially affected by the-superposed cur rents in the said derived circuits, means to indicate the average difierential effects of the said superposed currents on the said actuating elements during a predetermined time period, and integrating mechanism controlled by the said indicating means.

8. A wattmeter indicator comprising a pair ofvexpansion tubes with suitable conductors and heated by pairs of derived currents respectively. proportional to the voltage and to the amperage of the circuit to be measured and superposed difierentially in such conductors arranged for such heating, means to adjust the time lag of such heating, andmeans to continually indicate the condition of relative temperature of such tubes, substantially as described.

9. The combination with a pair of cir-.

age oi the current to be measured, of a Wattmeter indicator comprising two elements heated respectively by the added derived currents and by the derived currents mutually opposed, an indicator moved by the relative expansion of said elements during a definite time period and an integrating device in turn governed by said indicator.

10. The combination with a pair of circuits traversed respectively by derived currents proportional to voltage and to amperage of the current to be measured, of a watt-meter indicator comprising two expansion tubes having the ratio of their heatstoragecapacity to their heat-dissipating capacity adjustable, and heated respectively by combining said derived currents and by opposing the derived currents, an indicator moved by the relative expansion of said tubes and a maximum demand index moved by the indicator. Y Y

11. A wattmeter indicator comprising two expansion elements heated respectively by a derived current proportional to yoltage and a derived current proportional to amperage taken from the current to be measured, said derived currents acting in conjunction to heat one of said elements and in opposition to heat the other of said elements and means to introduce an adjustable time lag in the response of said elements V without lessening the efliciency.

12. A wattmeter indicator comprising two corrugated tubes filled with liquid, electric conductors arranged to heat the liquid, apivotally mounted movable pointer connected to the free ends of the tubes, an

indicator, a motor therefor and gearing in-- differentially heated-thereby, a heat expansion device comprising a longitudinal ex.-

pansibletube containing liquid and having a non-expansible portion'of larger volume 'than the expansible portion, substantially as and for the purpose described.

I 14. "A slow responding wattmeter com prising a heat absorbing element of adjustable capacity, an indicating device operated by the elfect of such heat absorption, whereby the eflect of energy absorptlon may be delayed for any desired predetermined timeperiod.

15. A slow responding thermo wattmeter including a plurality of devices expanded by absorption of energy in the form of heat,

means to indicate the relative expansion of said absorbing devices, and means to definitely fix and control the time lag of response, substantially as described.

1 6. A slow-responding .meter compr slng a pair of energy yieldingelements,- a pair of energy absorbing devices respectively associated therewith and adapted to receive and temporarily retain the energy absorbed therefrom, and means for-indicating the diiference between the average amounts of energy absorbed respectively by the said devices'in a predetermined period of time.

'In testimony whereof I have hereunto signed my name in the presence of'the two subscribing witnesses.

' PAUL M. LINCOLN. Witnesses FREDK. S'TAUB,

Jo. BAILY BROWN. 

